An interesting fact: The primary official language for international postal services is French. Anything properly addressed in French cannot be refused. English was also added as an official language but only as late as in 1994. These days there are systems that are capable to recognize many different languages but they might not be working everywhere so limiting yourself to writing (at least) country name in French or English is a good idea.
Also the last line should be just the name of a country, capitalised. Some of the countries require to capitalise all letters, not just the country.
On the UPU page you can find examples of addressing in accordance to a specific country's format. Note, the addresses are stripped off of the country, that should be, as already mentioned, placed in the last line.
Finally it's always a good idea to go to your local postal office and ask how to properly address your mail. Let me tell an anecdote here. My father, located in Lodz, the third largest city in Poland, had to send some business mail to the British Virgin Islands about 10 years ago. So he wrote the address and went to the post office to send it. The lady at the counter deck looked at the address and said:
There is no such country as British Virgin Islands. There are Easter Islands, Islands of Cape Verde, but no British Virgin Islands (in Polish all those names contain the word "Islands").
So my father went back to the office, and discovered that French is the main language. So he went once again to the post office with a mail readdressed in French, but he got refused again. He asked for a manager, explained everything and the manager eventually accepted the postage claiming she will make sure it will leave the post office with no further obstruction.
After a few days, the mail was returned with a Warsaw postal stamp (Polish capital city) and annotation "There is no such country". My father's conclusion was "the British Virgin Islands might be a tax paradise, because it is not possible to send any debt reminders there".